The present disclosure relates generally to a fluid flow control apparatus, and particularly to a fluid flow control apparatus having redundant fluid flow drivers.
Some heat transfer systems may employ forced convection heat transfer techniques for removing heat from a heat generator, such as a printed circuit board or an electronic cabinet for example, where the forced convection is achieved by driving a fluid across a heat sink that is in thermal contact with the heat generator. In an exemplary heat transfer system, air may be the fluid and a fan may be the fluid flow driver. In an effort to enhance the reliability of systems employing heat generators, or where maintenance downtime of such systems is of concern, redundant fans may be employed so that one fan may continue to run if another becomes non-operational. However, in the event that one of the redundant fans becomes non-operational, backwards flow of air through the non-operational fan may result, which may reduce the effectiveness of the heat exchanger, and may produce a reverse rotation of the non-operational fan that a monitoring system may then falsely indicate as a properly operating fan. In an attempt to alleviate such false indications, back flow limiting devices have been employed that use a set of louvers to block the back flow of air through a non-operational fan. However, with such limiting devices there may still be present a degree of flow turbulence and back pressure that could reduce fluid flow rates and impact the heat transfer characteristics of the heat transfer system, and such limiting devices may require the use of a large fan for operation of the limiting device itself. Accordingly, there is a need in the art for a fluid flow control apparatus that overcomes these drawbacks.